diff --git a/changelog.d/9987.misc b/changelog.d/9987.misc
new file mode 100644
index 000000000..02c088e3e
--- /dev/null
+++ b/changelog.d/9987.misc
@@ -0,0 +1 @@
+Remove unnecessary property from SQLBaseStore.
diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index 3d98d3f5f..0623da9aa 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -14,7 +14,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
-import random
 from abc import ABCMeta
 from typing import TYPE_CHECKING, Any, Collection, Iterable, Optional, Union
 
@@ -44,7 +43,6 @@ class SQLBaseStore(metaclass=ABCMeta):
         self._clock = hs.get_clock()
         self.database_engine = database.engine
         self.db_pool = database
-        self.rand = random.SystemRandom()
 
     def process_replication_rows(
         self,
diff --git a/synapse/storage/databases/main/registration.py b/synapse/storage/databases/main/registration.py
index 6e5ee557d..e5c5cf8ff 100644
--- a/synapse/storage/databases/main/registration.py
+++ b/synapse/storage/databases/main/registration.py
@@ -14,6 +14,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
+import random
 import re
 from typing import TYPE_CHECKING, Any, Dict, List, Optional, Tuple, Union
 
@@ -997,7 +998,7 @@ class RegistrationWorkerStore(CacheInvalidationWorkerStore):
         expiration_ts = now_ms + self._account_validity_period
 
         if use_delta:
-            expiration_ts = self.rand.randrange(
+            expiration_ts = random.randrange(
                 expiration_ts - self._account_validity_startup_job_max_delta,
                 expiration_ts,
             )